<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
    img{
        width: 100%;
        border: 1px solid #333;
    }
    .row{
        border: 1px solid #333;
    }
    .row>div{

    }
    
    </style>
</head>
<body>
    <!-- 
        pc   一行4列
        pad  一行2列
        mobile 一行一列
    -->
    <div class="container">
        <div class="row">
            <div class="col-md-3 col-sm-6">
               <img src="images/timg.jpg" alt="">
            </div>
            <div class="col-md-3 col-sm-6">
                <img src="images/timg.jpg" alt="">
            </div>
            <div class="col-md-3 colsm-6">
                <img src="images/timg.jpg" alt="">
            </div>

        </div>
    </div>
</body>
</html>